diff --git a/pyproject.toml b/pyproject.toml
index 5c1f8d5..dfa5d8a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -41,6 +41,9 @@ Source = "https://github.com/trailofbits/rfc8785.py"
 [tool.flit.module]
 name = "rfc8785"
 
+[tool.flit.sdist]
+include = ["test"]
+
 [tool.mypy]
 mypy_path = "src"
 packages = "rfc8785"